(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 15 of 38

Thread: Dripping thermal expansion relief value

Hybrid View

  1. #1
    DIY Junior Member psyq's Avatar
    Join Date
    Oct 2013
    Location
    Vancouver, BC
    Posts
    8

    Default Dripping thermal expansion relief value

    Correct me if I get my terminology wrong. I believe I have a dripping thermal expansion relief value on my hot water heater. My precious and quite costly BTUs are going down the drain
    The main line has a pressure reducing value. Does it look like I need a thermal expansion tank? Should I pressure test the system?

    Lucky I have a nifty picture to illustrate:
    Name:  heater.jpg
Views: 105
Size:  40.0 KB

  2. #2
    DIY Senior Member Reach4's Avatar
    Join Date
    Sep 2013
    Location
    IL
    Posts
    1,247

    Default

    A pressure gauge would be interesting. http://www.homedepot.com/p/Watts-3-4...IWTG/100175467 http://www.homedepot.com/p/Rain-Bird...-P2A/100575619
    Connect it to the faucet on your laundry tub or washing machine hot tap. I don't know what temperature the gauge is good for, but if you don't run the water, things should stay fairly cool at the gauge. The point is, does your pressure rise a lot when the water heater goes on? What pressure is present on the hot water when your relief valve leaks? You might just need a new relief valve.

    You might need an expansion tank. The gauge will be informative.

  3. #3
    DIY Junior Member psyq's Avatar
    Join Date
    Oct 2013
    Location
    Vancouver, BC
    Posts
    8

    Default

    I don't have anywhere easy to screw a pressure gauge in (no laundry tub and washer would be a PITA to get to). What about to the drain for the tank itself?

  4. #4
    Forum Admin, Expert Plumber Terry's Avatar
    Join Date
    Aug 2004
    Location
    Bothell, Washington
    Posts
    14,191
    Blog Entries
    1

    Default

    The drain on the water heater is a hose thread. There is no problem putting a pressure gage on a water heater.

    In your case, an expansion tank would help.
    Unless you PRV has a bypass, it can allow pressure build up when the water heats.
    For starters, you need to know if the PRV is even working.
    Last edited by Terry; 10-22-2013 at 01:07 PM.

  5. #5
    DIY Senior Member Reach4's Avatar
    Join Date
    Sep 2013
    Location
    IL
    Posts
    1,247

    Default

    Good idea. However that will be hotter than those other places. Maybe put a garden hose in the path if you are concerned about overheating the gauge. The downside of that the flexible might be that the hose could serve as bit of an expandable pressure tank, messing up your test. Maybe the packaging on the gauge will indicate a temperature range.

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    Location
    New England
    Posts
    21,376

    Default

    The gauge will handle being on the tank's drain but flush the thing first, or you will probably clog the gauge with sediment when you open the drain valve. It's you that may have problems with the heat, so would need gloves or pliers to maybe install or remove it.

    You can often pick up an adapter for a sink aerator, take the aerator off, then screw in the adapter then install the pressure gauge to it.

    The cable's in the way, is that a T&P valve on the top of the WH? It should be. It will have a test, release lever on the top and probably a tag.

    A pressure relief valve inline to a WH without an expansion tank is a problem waiting to happen.

    I do not know how common closed supply systems are in Canada, but if you have one, and do not have an expansion tank, you should add one, otherwise, there is no way you'll ever stop that valve from releasing pressure while the WH is running...water expands when it is heated, and if there's no place for it to go (a closed system means it can't push back out into the supply, which is one reason they make them, to protect the water supply to others in case yours became polluted some way), the pressure WILL rise, and the pressure relief valve is just doing what it should be. An expansion tank, properly precharged, prevents that pressure rise. You'll need a pressure gauge to determine the proper precharge on an expansion tank. With one, you could probably get rid of the pressure relief valve, and install the expansion tank in its place.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  7. #7
    DIY Senior Member Reach4's Avatar
    Join Date
    Sep 2013
    Location
    IL
    Posts
    1,247

    Default

    Quote Originally Posted by jadnashua View Post
    With one, you could probably get rid of the pressure relief valve, and install the expansion tank in its place.
    You want to re-think that suggestion! Do not get rid of the relief valve.

    If you install an expansion tank, there is no technical reason that it has to be installed at the water heater. It could be on any water heater line that does not have a valve between it an the water heater. I said "technical reason" because I don't know what the codes say about that.

  8. #8
    DIY Junior Member psyq's Avatar
    Join Date
    Oct 2013
    Location
    Vancouver, BC
    Posts
    8

    Default

    Quote Originally Posted by jadnashua View Post
    The cable's in the way, is that a T&P valve on the top of the WH? It should be. It will have a test, release lever on the top and probably a tag
    It is. It works, I tested it right away when I heard the dripping.

Similar Threads

  1. Help!! Pressure Relief Valve Dripping!!
    By vginotes in forum Boiler Forum
    Replies: 4
    Last Post: 02-08-2013, 01:36 PM
  2. Thermal Expansion
    By MrBillyd in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 7
    Last Post: 05-04-2012, 10:05 AM
  3. Thermal expansion queston
    By DIY in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 5
    Last Post: 03-15-2010, 01:24 PM
  4. Thermal Expantion Tank vs Thermal Expansion Relief Valve?
    By Grayfeathers in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 8
    Last Post: 05-07-2009, 10:08 PM
  5. thermal expansion
    By ally68 in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 1
    Last Post: 01-31-2005, 04:01 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •